While Google has just announced in it's official blog, that they are working hard to make ads more interesting, not everyone will be happy to discover that this means, that Google will be tracking your web surfing habits in more and more detail to achieve that.
So what are the alternatives? Yahoo and MSN search engines have been doing this already too, and frankly in my personal experience the quality of the search results is not as good as Google's.

In theory a meta search engine would be ideal, as it searches several search engines in one go for you, giving you the best results from all major search engines without exposing your IP address and/or cookies to any of them.
The problem is, most meta search engines I have come across until now are very slow, as they are often run by smaller companies without the resources to invest in enough powerful servers to provide a fast search. Also the presentation of the search results is often not very good, and there is the small matter that now you have to trust the meta search engine owners not to track you searches.

screenshot of ixquick.com home page

Meet ixquick.com:

According to Wikipedia, "Ixquick is a metasearch engine based in New York and the Netherlands, and has provided over 120 million searches since 2004.", but even more interestingly "Ixquick.com became the first search engine to delete private details of its users. IP addresses and other personal information are deleted within 48 hours of a search.
Ixquick also does not share its users' personal information with other search engines or with the provider of its sponsored results. As of January 29th 2009 Ixquick no longer records users' IP addresses at all."
Even better, it's also available via https, which means your ISP (think Phorm), or your employer cannot normally track what you are searching (beware of sneaky SSL gateways or proxies though!).

So how's the search experience?

I have been using Ixquick and I like it, it's fast as a normal search engine and the ranking and choice of results is generally very good. It also provides a powerful advanced syntax, that reminds me a bit of the advanced Altavista search syntax of the good old times, when the Internet was still young and innocent.
At the time of writing Ixquick searches for you on the following search engines and directories: Yahoo, MSN, Ask/Teoma, All the Web, Lycos, Exalead, Gigablast, Open Directory, Qkport and Wikipedia, but sadly not Google.
While it would have been perfect if it searched Google too, I have found that generally the aggregated results from the search engines Ixquick provides, match the quality of the results that Google provides on it's own.